This happens to me every time I get into high progress with my mod. Last time it happened I had to start rebuilding my mod from the very beginning. In later times it was just a bug in FLMM 1.31 that I just had to rename the folder. It stopped happening ever since I started using FLMM 1.4, but surprise surprise!
Since I'm not able to use FLSpit or Spew, I'm asking for your help with it. If I won't find any help, I might consider giving a lucky modder all my files (systems I worked on for hours, models I made, a collection of plugins, etc) because I'm NOT rebuilding it.